fn main() {
    let v1 = vec![1, 2, 3];
    let mut u = v1.iter();
    loop {
        match u.next() {
            Some(e)=>{
                println!("{}", e+e);
            },
            None=>{
                println!("u_iterator is used");
                break;
            }
        }
    }

    let v2 = vec![1, 2, 3];
    let v2_iter = v2.iter().map(|x| (x+1).to_string());
    for z in v2_iter{
        println!("{}", z);
    }

    let a1 = vec![1, 2, 3];
    let a2 = vec![10, 20, 30];
    let zp = a1.iter().zip(a2.iter());
    for x in zp{
        println!("{:?}", x);
    }

}
